Australian researchers believe they may have found a link between where women live and their chance of developing breast cancer.

Scientists from the Westmead Cancer Institute reviewed the incidence of breast cancer and local government areas on mainland Australia.

They found women in southern states were much more likely to develop the disease, suggesting low vitamin D levels, due to less sunlight, might be to blame.

"Amazingly, what we found was that people who lived south of latitude 30, or around Coffs Harbour on the east coast of New South Wales, had a doubling of the incidence of breast cancer," said Professor John Boyages from the Macquarie University Cancer Institute.

Low vitamin D levels can cause other problems, including increasing the risk of multiple sclerosis.

But doctors have stressed it is too early for women in southern states to start taking vitamin D supplements.

"We don't have all the answers. We don't even know if it's cause and effect," Professor Boyages said.

The research has been presented at the Sydney International Breast Cancer Congress.

A further study is planned in which women with breast cancer will take vitamin D supplements to see if it helps their prognosis.

Doctors advise the best way to prevent breast cancer is to maintain a healthy weight, limit alcohol and get regular mammograms.